Tomorrow will be an agonising day for museum custodian Kay Cooper. In a painstaking - and painful - attempt accurately to recreate one of the museum's prize exhibits, she will be spending several hours shoe-horned into a 16th-century costume, complete with a starched cotton ruff and whalebone stays.

Her costume is based on one worn by the Countess of Newcastle in a portrait by Jacobean artist William Larkin, which is on show at Ranger's House, Chesterfield Walk, Blackheath.

Mrs Cooper and fellow custodian Tony Lee will both be in costume as part of a family fun day which is to be held in nearby Greenwich park this weekend.

The black brocade gown, complete with an underskirt, or kirtle, of braided taffeta, is made from almost 10 metres of fabric.

'It's absolute hell to wear,' said Mrs Cooper yesterday. 'It is tightly fitted and boned and the back really hurts.'

Mr Lee will be wearing a costume based on one worn by Thomas Sackville, the 17th-century poet and dramatist, which used two metres of

brocade for the doublet and three metres for the breeches.

Both costumes have been made by dressmaker Sandra Ward, who is a member of the Sealed Knot, a society which studies the history and events of the English Civil War.